Fiber optics printed circuit board assembly surface cleaning and roughening

ABSTRACT

The present disclosure generally relates to printed circuit boards or printed circuit board assemblies for fiber optic communications. In one example, an optoelectronic assembly may include a printed circuit board including a laser-roughened area, at least one optoelectronic component coupled to a surface of the printed circuit board, and an optical component attached to the printed circuit board. The coupling area may be defined by the optical component contacting the printed circuit board, and the laser-roughened area may be positioned entirely within the coupling area defined by the optical component contacting the printed circuit board.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application that claims priority toU.S. patent application Ser. No. 16/007,855 filed Jun. 13, 2018, titledFIBER OPTICS PRINTED CIRCUIT BOARD ASSEMBLY SURFACE CLEANING ANDROUGHENING, which has issued as U.S. Pat. No. 10,816,741 and whichclaims priority to Chinese Patent Application No. 201810575121.7, filedJun. 6, 2018, titled FIBER OPTICS PRINTED CIRCUIT BOARD ASSEMBLY SURFACECLEANING AND ROUGHENING, and which are all incorporated by reference intheir entirety.

BACKGROUND

The present disclosure generally relates to printed circuit boards orprinted circuit board assemblies for fiber optic communications. Inparticular, the present disclosure relates to modifications to a surfaceof printed circuit boards to facilitate manufacture of optoelectronicassemblies, which may result in improved optoelectronic assemblies thatincorporate aspects described herein.

Printed circuit boards (PCBs) mechanically support and electricallyconnect electrical components using conductive couplings such as traces,tracks, pads and/or other features etched from one or more layers ofelectrically conductive material, such as copper, attached to one ormore layers of a non-conductive substrate. Components are generallysoldered onto the PCB to both electrically connect and mechanicallyfasten them to it. PCBs may be used in optoelectronic assemblies thatconvert electrical signals to optical signals, optical signals toelectrical signals, or both. Optoelectronic assemblies may be used, forexample, in fiber optic communication to exchange data at increasedrates.

In optoelectronic assemblies that implement PCBs, both electrical andoptical components may be coupled to the PCB. However, PCB assemblieswith both electrical and optical components may pose variousmanufacturing challenges that may need to be addressed to effectivelyproduce optoelectronic assemblies.

The claimed subject matter is not limited to embodiments that solve anydisadvantages or that operate only in environments such as thosedescribed above. This background is only provided to illustrate examplesof where the present disclosure may be utilized.

SUMMARY

The present disclosure generally relates to modifications to a surfaceof a printed circuit board (PCB) to facilitate manufacture ofoptoelectronic assemblies, which may result in improved optoelectronicassemblies that incorporate aspects described herein.

In one non-limiting example, an optoelectronic assembly may include aprinted circuit board including a laser-roughened area, at least oneoptoelectronic component coupled to a surface of the printed circuitboard, and an optical component attached to the printed circuit board.The coupling area may be defined by the optical component contacting theprinted circuit board, and the laser-roughened area may be positionedentirely within the coupling area defined by the optical componentcontacting the printed circuit board.

This Summary introduces a selection of concepts in a simplified formthat are further described below in the Detailed Description. ThisSummary does not identify key features or essential characteristics ofthe claimed subject matter, and should not be used as an aid indetermining the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top schematic view of an example printed circuit boardassembly (PCBA);

FIG. 1B is a top schematic view of a portion of the PCBA of FIG. 1A;

FIG. 1C is another top schematic view of a portion of the PCBA of FIG.1A;

FIG. 2A is cross-sectional schematic view of a portion of the PCBA ofFIG. 1A;

FIG. 2B is cross-sectional schematic view of a portion of the PCBA ofFIG. 1A;

FIG. 3 is flow chart of an example method of forming a PCBA;

FIG. 4 is flow chart of another example method of forming a PCBA;

FIG. 5A is a top schematic view of the PCBA of FIG. 1A with an opticalcomponent; and

FIG. 5B is a side schematic view of the PCBA of FIG. 5A.

DETAILED DESCRIPTION

The present disclosure generally relates to printed circuit boards orprinted circuit board assemblies for fiber optic communications.Assemblies that incorporate printed circuit boards (PCBs) may bereferred to as printed circuit board assemblies (PCBAs). In particular,the present disclosure relates to modifications to the surface of PCB tofacilitate manufacture of optoelectronic assemblies, which may result inimproved optoelectronic assemblies that incorporate aspects describedherein.

PCBs may be implemented in optoelectronic assemblies configured forfiber optic communication. Optoelectronic assemblies that implement PCBsmay include both electrical and optical components that are coupled tothe PCB. However, PCB assemblies with the electrical and opticalcomponents may pose various manufacturing challenges that interfere witheffective and efficient production of optoelectronic assemblies.

For example, certain optical components such as lenses, may be opticallyaligned with other optical components. Therefore the optical componentsmay need to be more precisely positioned and attached to the PCB thanelectrical components. Furthermore, it may not be practicable to attachoptical components to the PCB with solder. Therefore, optical componentsmay be attached to the PCB in other manners. However, additionalchallenges arise in coupling optical components to the PCBs in acost-effective and robust manner.

In some circumstances, it may desirable to mechanically couple opticalcomponents to the surface of a PCB, for example, using an adhesive orother suitable attachment process. For instance, in some conventionalprocesses to mechanically couple the optical components to the surface,the PCB may be untreated. The untreated PCB includes a substantiallysmooth surface that is not cleaned. If the surface of the PCB iscontaminated, the optical component may not sufficiently bond to thePCB. Furthermore, if the surface of the PCB is contaminated when theoptical component is bonded to the PCB, the resulting bond between thePCB and the optical component may be relatively weak. In suchcircumstances, the bond may break over time, for example, duringsubsequent processing of the PCB to form the optoelectronic assembly.Additionally, the weak bond may break after the optoelectronic assemblyis manufactured, for example, during operation of the optoelectronicassembly. Furthermore, in such circumstances the optoelectronic assemblymay fail prematurely because of a weak bond caused by the substantiallysmooth surface of the PCB or the contaminants on the surface of the PCBleft during manufacturing.

Some PCBAs implement through-hole technology (THT). THT refers to amounting process for attaching electrical components using leads thatextend from the electrical components. The leads are inserted into holesformed in the PCB and soldered to pads on the opposite side of the PCB.Other PCBAs implement surface-mount technology (SMT). SMT is a mountingprocess in which components are mounted or placed directly onto thesurface of the PCBs. SMT components are usually smaller than THTcomponents because they have either smaller leads or no leads at all.Generally, SMT speeds up the manufacturing process when compared to THT.However, use of SMT in some circumstances increase the risk of defectsdue to component miniaturization and denser packing of components on thePCB. In such circumstances, detecting defects (e.g., contaminants ordefective bonds) may also be more difficult. Although both SMT and THTmay be implemented in various circumstances, SMT has largely replacedTHT in manufacture of PCBAs.

The surface of the PCB may be contaminated during the normal course ofmanufacturing, for example, during SMT or THT processes. Contaminantssuch as flux, oil, dust, adhesive, or other contaminants may bedeposited on the surface of the PCBs as the PCBs are being formed. Suchcontaminants may be difficult to detect, during and after manufacturing,and may lead to the weak bonds that are also difficult to detect. Forinstance, the contaminants may be invisible to the human eye, using amicroscope, or using other detection methods. Thus, it may be difficultto determine whether a surface of a PCB is contaminated before bonding.Furthermore, it may be difficult to remove contaminants that are notvisible or detectable, and to determine whether or not the contaminantswere successfully removed.

Even if the surface of the PCBs does not include contaminants, in somecircumstances the PCB may not be well-suited for attaching components toits surface. For example, the surface of the PCB may be relativelysmooth. Adhesives may not bond as well to smooth surfaces as to roughsurfaces. Some PCBs may include a solder mask, which is a thinlacquer-like layer of polymer that is applied to the surface of the PCB.The solder mask may be used to protect electrically conductive traces onthe PCB from oxidation and to prevent or reduce undesired electricalconnections between adjacent conductive traces that are positionedrelatively close to one another. The solder mask may also be relativelysmooth, and adhesives may form relatively poor bonds with the soldermask, for example, when coupling optical components to the PCB.

Accordingly, the present disclosure includes configurations to modifythe surface of PCBs to remove contaminants (e.g., clean the surface)and/or increase the roughness of the surface. In particular, a laser maybe used to remove contaminants on the surface of the PCB. Furthermore,the laser may be used to remove a portion of the PCB (e.g., a portion ofa layer of the PCB, an entire layer of the PCB, or more than one layerof the PCB). Additionally, the laser may be used to increase theroughness of the surface of the PCB.

Aspects described herein may improve bonding between the PCB andcomponents attached to the PCB (e.g., optical components or others)using, for example, adhesives or other suitable attachment processes.Specifically, bonding between the PCB and a component may be improvedbecause the laser removes contaminants from the surface of the PCBand/or increases its roughness. This may improve the strength of thebonds between the PCB and optical components, which in turn may decreasethe likelihood that the bonds will break during and after manufacturing.Furthermore, assemblies implementing the concepts described herein maybe less likely to fail prematurely as result of broken bonds between thePCB and attached components.

In addition, the laser may visibly modify the surface of the PCB, makingit easier to determine whether contaminants have been removed from acertain area on the PCB and/or whether the area has been roughened. Forexample, the laser may change a color and/or a texture of the surface ofthe PCB where the laser is applied. In particular, the color and/or thetexture of the surface may be different in an area because all or aportion of a layer of the PCB may be removed by the laser. Suchconfigurations may also facilitate positioning of components to becoupled to the PCB, because the visibly modified surface may indicatewhere the component should be attached to the PCB.

Using a laser to modify the surface of the PCB may avoid damagingcomponents coupled to the PCB. In particular, some components (e.g.,electrical components or others) may be attached to the PCB before thelaser is applied to the surface of the PCB. The laser may be accuratelycontrolled to apply the laser in specific areas on the surface of thePCB. Accurate control of the laser may avoid the components that arealready coupled to the PCB so these components are not damaged. Use ofthe laser may provide some advantages relative to othercontamination-removal processes. For instance, other processes forremoving contaminants from the PCB such as solvent cleaning, plasmacleaning, etc. may risk damaging components on the PCB.

Reference will be made to the drawings and specific language will beused to describe various aspects of the disclosure. Using the drawingsand description in this manner should not be construed as limiting itsscope. Additional aspects may be apparent in light of the disclosure,including the claims, or may be learned by practice.

FIG. 1A is a top schematic view of an example of a PCBA 100. The PCBA100 may include a PCB that includes an insulating substrate 102 and asurface 118. Various components, such as electrical components 104 a-e,may be positioned on and mechanically coupled to the substrate 102. Theelectrical components 104 a-e may be electrically coupled by conductivecouplings 106 a-e. The conductive couplings 106 a-e may be traces,tracks, pads and/or other features etched from one or more layers ofelectrically conductive material, such as copper. The electricalcomponents 104 a-e may be soldered to electrically and mechanicallycouple them to the PCBA 100.

The PCBA 100 may include a single layer or multilayer configuration. Ifthe PCBA 100 is a single layer PCB, then it may include one layer of theinsulating substrate with conductive couplings positioned on one or bothsides. If the PCBA 100 is a multilayer PCB, then it may include multiplelayers of insulating substrate, and conductive couplings may bepositioned on and/or in between the multiple layers.

In some configurations, the PCBA 100 may include a solder mask, which isa layer applied to the surface 118 of the PCBA 100. The solder mask maybe a layer on the surface 118 or proximate the surface 118 of the PCBA100. The solder mask may protect portions of the PCBA 100, such as theconductive couplings 106 a-e. For example, the solder mask may protectthe conductive couplings 106 a-e from oxidation and to prevent undesiredelectrical connections between adjacent conductive couplings (e.g., 106a and 106 d) that are positioned relatively close to one another. Thesolder mask may be relatively smooth, and adhesives may form relativelypoor bonds with the solder mask, for example, when components areattached to the PCBA 100.

In some circumstances, the solder mask may be applied to the PCBA 100using a mask or silk screening technique. The solder mask may be appliedas an epoxy liquid through a silkscreen pattern onto the PCBA 100.Additionally or alternatively, the solder mask may be applied using anysuitable technique, such as liquid photoimageable solder mask (LPSM) ordry film photoimageable solder mask (DFSM). Once applied, the soldermask may be cured, for example, using a thermal or ultra violet curingprocess. Openings may be formed in the solder mask using any suitableprocess, such as photolithography.

The PCBA 100 may include optoelectronic components 108. In suchconfigurations, the PCBA 100 may be included in an optoelectronicassembly used for fiber optic communication, although the conceptsdescribed herein may be implemented in any suitable PCBA. Theoptoelectronic components 108 may include components related to theconversion of electrical signals to optical signals, optical signals toelectrical signals, or both. For example, the optoelectronic components108 may include a receiver or receiver array configured to receiveoptical signals and to generate corresponding electrical signals. Inanother example, the optoelectronic components 108 may include atransmitter or transmitter array configured to receive electricalsignals and to generate corresponding optical signals.

The optoelectronic components 108 may include or may be coupled tocomponents related to optical transmitters and receivers. Some examplesof the components may include amplifiers (e.g., transimpedanceamplifiers, limiting amplifiers, or others), clock and data recovery(CDR) circuits, digital signal processing circuits, drivers,digital-to-analog converter (DAC) circuits, modulators, or othersuitable components. In some configurations, such components may beincluded in the electrical components 104 a-e.

As explained above, the optoelectronic assembly may include electricalcomponents 104 a-e and/or optoelectronic components 108 coupled to thePCBA 100. The optoelectronic assembly may also include opticalcomponents optically coupled or optically aligned to the optoelectroniccomponents 108. The optical components may include lenses, filters,collimators, mirrors, polarizers, or any other suitable component usedin optoelectronics. The optical components may be configured to performan optical function such as direct, focus, collimate, modulate,multiplex, or demultiplex optical signals travelling to or from theoptoelectronic components 108.

At least some of the optical components may be mechanically coupled tothe PCBA 100. As illustrated, an optical component may be mechanicallycoupled to the PCBA 100 at coupling area 110. The coupling area 110 maycorrespond to the size and/or shape of an optical component to becoupled with the PCBA 100. In the illustrated configuration, thecoupling area 110 is rectangular and annular (e.g., a rectangularannulus) with rounded corners. The coupling area 110 may correspond to arectangular optical component that is to be mechanically coupled to thePCBA 100 and optically coupled to the optoelectronic components 108. Inother configurations, the coupling area 110 may be any suitable shape orsize, and the configuration of the coupling area 110 may depend on theshape and size of the optical component. In the illustrated example, theoptical component may include a lens, although any suitable componentmay be coupled to the PCBA 100 according to the concepts described inthis disclosure.

The PCBA 100 may include a laser-roughened area 112. The laser-roughenedarea 112 may correspond to the size and/or shape of the coupling area110 or the optical component to be coupled with the PCBA 100. In theillustrated configuration, the laser-roughened area 112 is rectangularand annular (e.g., a rectangular annulus) with rounded corners,corresponding to the coupling area 110. The laser-roughened area 112 maybe positioned entirely within the coupling area 110 as shown, althoughother configurations may be implemented. In other configurations, thelaser-roughened area 112 may be any suitable shape or size, and theconfiguration of the laser-roughened area 112 may depend on the shapeand size of the coupling area 110, the optical component, or both.

The laser-roughened area 112 may be formed by a laser applied to thesurface 118 of the PCBA 100 (e.g., lasering the surface 118 of the PCBA100), as described in further detail below. The laser may be used toremove a portion of the PCBA 100 to form the laser-roughened area 112.In particular, the laser may be used to remove a portion of a layer ofthe PCBA 100, an entire layer of the PCBA 100, or more than one layer ofthe PCBA 100. For example, the laser may be used to remove between about1 and 30 micrometers (μm) of the PCBA 100 (e.g., depth or height of theremoved portion). In some configurations, the power, intensity and/orwavelength of the laser may be selected to remove a desired amount ofthe PCBA 100. Additionally or alternatively, the laser may be appliedrepeatedly a given area to remove additional layers or portions of thePCBA 100. Accordingly, additional portions may be removed each time thelaser is applied to an area on the PCBA 100. (e.g., the laser-roughenedarea 112).

The power, intensity and/or wavelength of the laser used to form thelaser-roughened area 112 may be selected to be sufficiently high toincrease the roughness of the surface. Additionally or alternatively,the power, intensity and/or wavelength of the laser used to form thelaser-roughened area 112 may be selected to be sufficiently high toremove or decompose contaminants without damaging the PCBA 100 and/orthe components coupled to the PCBA 100, such as the electricalcomponents 104 a-e and the optoelectronic components 108. The desiredpower, intensity and/or wavelength of the laser may depend on materialsincluded in the PCB (e.g., layers of the PCB), materials of thecontaminants, materials of components coupled to the PCB, or anysuitable combination thereof. In one example, the laser may be anultraviolet laser, for example, a laser emitting electromagneticradiation within a range of ultraviolet wavelengths. In somecircumstances, ultraviolet wavelengths may include wavelengths between100 nanometers (nm) and 400 nm. In some configurations, the laser may bea 355 nm wavelength laser, although other suitable configurations may beimplemented. Additionally or alternatively, in some configurations thelaser may include a laser power of 3 Watts (W).

The laser-roughened area 112 of the surface 118 of the PCBA 100 may berougher than a remaining area of the surface 118 of the PCB. Thelaser-roughened area 112 of the surface 118 of the PCB may have a largerarithmetical mean deviation of the assessed profile than the remainingarea of the surface 118 of the PCB. The difference between thelaser-roughened area 112 and the remaining area of the surface 118 ofthe PCB may be visually perceptible. Accordingly, it may be possible tovisually determine whether or not portions of the surface 118 has beenroughened and/or whether contaminants have been removed in certain areason the surface 118.

FIG. 1B is a top schematic view of a portion of the PCBA 100 of FIG. 1A.In particular, FIG. 1B illustrates a portion of the PCBA 100, denoted bycircle 1B in FIG. 1A. In FIG. 1B, the optoelectronic components 108, thecoupling area 110, and the laser-roughened area 112 are shown in furtherdetail. As introduced above, the laser-roughened area 112 may bepositioned entirely within the coupling area 110. In the illustratedconfiguration, the laser-roughened area 112 is concentrically positionedwithin the coupling area 110, although other configurations may beimplemented. The optoelectronic components 108 may be electricallycoupled to other components of the PCBA 100 with conductive couplings106 a-d.

As mentioned, the optical component may include a lens. In someconfigurations, the optical component may partially or wholly enclosethe components positioned in an area 114 inside of the coupling area110. For example, the optical component may define a cavity to enclosethe optoelectronic components 108 between the optical component and thePCB of the PCBA 100. In such configurations, the optical component mayhermetically seal the optoelectronic components 108 or other componentspositioned in the area 114. The laser-roughened area 112 and/or thecoupling area 110 may surround the optoelectronic components 108 in aplane defined by the PCB of the PCBA 100. In addition, the opticalcomponent may be optically aligned with the optoelectronic component.

In some configurations, the PCBA 100 of FIGS. 1A-1B way be implementedin optoelectronic assemblies that implement PCBAs. For example, the PCBA100 may be implemented in optoelectronic modules for use intransceivers, transmitter optical subassemblies (TOSAs), receiveroptical subassemblies (ROSAs), active optical cables, and others. Insome configurations, the optoelectronic modules may comply with the Gen4QSFP or Gen4 QSFP+ form factor.

FIG. 1C is a top schematic view of a portion of the PCBA 100. Inparticular, FIG. 1C illustrates a portion of the PCBA 100, denoted byrectangle 1C in FIG. 1B. In FIG. 1B, the coupling area 110 and thelaser-roughened area 112 are shown in further detail. As shown, thelaser-roughened area 112 may overlap or be positioned over the couplingarea 110. In the configuration shown, the laser-roughened area 112 maybe smaller than the coupling area 110. In some configurations, thelaser-roughened area 112 may be between about 50% and about 75% of thesize of the coupling area 110, although other configurations may beimplemented. In other configurations, the laser-roughened area 112 maybe substantially the same size or larger than the coupling area 110.Furthermore, the laser-roughened area 112 may not be positioned fullywithin the coupling area 110. In such configurations, thelaser-roughened area 112 may partially overlap the coupling area 110.

FIG. 2A is a cross-sectional schematic view of a portion of the PCB ofthe PCBA 100. In FIG. 2A, the laser-roughened area 112 is shown infurther detail. As mentioned above, a laser may be used to increase theroughness of the surface 118 of the PCBA 100 and/or remove a portion ofthe PCBA 100. As shown in FIG. 2A, the PCBA 100 may include a layer 116positioned over the substrate 102 and defining the surface 118 of thePCBA 100. The laser may be applied to the surface 118 to remove aportion of the layer 116 to form the laser-roughened area 112. In theillustrated configuration, only a portion of the layer 116 is removed toform the laser-roughened area 112. However, in other configurations theentire layer 116 may be removed to form the laser-roughened area 112, oradditional layers (not shown) may be removed from the PCBA 100. In someconfigurations, the layer 116 may be a solder mask layer, or a portionof the solder mask. Accordingly, the solder mask may be the portion ofthe PCBA 100 that is cleaned and/or roughened. The solder mask may beabsent at the laser-roughened area 112 of the PCB or the PCBA 100.

FIG. 2B is a cross-sectional schematic view of a portion of the PCBA100. In particular, FIG. 2B illustrates the surface 118 of the PCBA 100before the laser is applied, denoted at 118 a, and after the laser isapplied, denoted at 118 b. As shown, the surface 118 a before the laseris applied is relatively smooth. In such circumstances, adhesives usedto bond, for example, optical components to the surface 118 a may notbond well, which may result in relatively weak bonds that mayprematurely fail. In contrast, the surface 118 b after the laser isapplied is rougher, as shown. In such circumstances, adhesives used tobond optical components (as described with reference to FIGS. 1A-1C) tothe surface 118 b may form stronger bonds between the optical componentsand the PCBs relative to the smooth surface 118A. Although any suitableadhesive may be used for bonding, in some configurations an epoxy may beimplemented.

One measure of surface roughness is the arithmetical mean deviation ofthe assessed profile or the mean roughness of the profile of thesurface, denoted as R_(a). In one example, the R_(a) roughness ofsurface 118 a may be less than 0.2 μm and the R_(a) roughness of surface118 b may be greater than 0.3 μm. Accordingly, the laser may increasethe roughness of the surface 118 by at least an R_(a) of 0.1 μm.However, in other circumstances, the surfaces 118 a, 118 b may haveother roughness values. For example, the surface 118 of the PCBA 100 mayhave any suitable roughness values. Furthermore, the laser may be usedto increase the roughness of the surface 118 less than or greater thanthe example values described above.

FIG. 3 is flow chart of an example method 300 of forming a PCBA and/ormodifying a surface of a PCB. The method 300 may be implement inconstruction of an assembly that includes a PCB such as the PCBA 100 ofFIGS. 1A-1B. Although illustrated as discrete blocks, various steps inFIG. 3 may be divided into additional steps, combined into fewer steps,or eliminated, depending on the desired implementation.

The method 300 may begin at step 302, in which a substrate may beprovided. For example, the substrate 102 of FIGS. 1A-1B may be provided.At step 304, conductive couplings may be formed on a surface of thesubstrate. For instance, referring to FIGS. 1A-1B, the conductivecouplings 106 a-e may be formed on a surface of the substrate 102. Anysuitable configuration may be used for forming the conductive couplings.For example, a layer of conductive material, such as copper, may bepositioned over the substrate, which may be non-conductive. Theconductive material may be etched or otherwise processed to remove aportion of the conductive material, and the remaining conductivematerial may form the conductive couplings on the surface of thesubstrate.

At step 306, one or more components may be coupled to the surface of thesubstrate. In some configurations, the components may be electricalcomponents and/or optoelectronic components. For example, referring toFIGS. 1A-1B, the electrical components 104 a-e and/or the optoelectroniccomponents 108 may be coupled to the surface 118 of the substrate 102.Accordingly, at least one optoelectronic component may be coupled to asurface of the PCB. In some configurations, the components may besoldered to the conductive couplings of the PCB, thereby mechanicallycoupling the components to the PCB and electrically coupling theelectrical components to the conductive traces.

At step 308, a solder mask may be applied over the substrate and/or theconductive couplings. The solder mask may be applied using any suitabletechnique. For example, in some configurations, the solder mask may beapplied using a mask or silk screening technique. The solder mask may beapplied as an epoxy liquid through a silkscreen pattern or mask onto thesurface of the PCB (e.g., over the substrate and/or the conductivecouplings). Additionally or alternatively, the solder mask may beapplied using any suitable technique, such as liquid photoimageablesolder mask (LPSM) or dry film photoimageable solder mask (DFSM). Onceapplied, the solder mask may be cured, for example, using a thermal orultra violet curing process. Openings may be formed in the solder maskusing any suitable process, such as photolithography. In someconfigurations, the solder mask may form the surface of the PCB,although in other configurations a solder mask may not be included inthe PCB.

At step 310, a laser may be applied to the surface of the substrate orthe PCB (e.g., lasering the surface). The laser may be applied to acertain area on the surface of the PCB. For example, the laser mayapplied on portions of the PCB where it may be desirable to remove ordecompose contaminants. In another example, the laser may applied onportions of the PCB where it may be desirable to increase the roughnessof the surface. In particular, the laser may be applied to a portion ofthe PCB where a component is to be coupled to the surface of the PCB. Insome configurations, the component is to be coupled to the surface ofthe PCB may be an optical component. The area where the laser appliedmay be a laser-roughened area, such as the laser-roughened area 112, andthe area where the component is coupled to the PCB may be a couplingarea, such as the coupling area 110. As shown, for example, in FIGS.1A-1C, the shape of the laser-roughened area may correspond to the shapeof the coupling area, and in some configurations the laser-roughenedarea is smaller than the coupling area.

Application of the laser (e.g., lasering) may remove at least a portionof a layer of the PCB and/or may increase the roughness of the surfaceof the printed circuit board. In some aspects, the laser may increasethe arithmetical mean deviation of the assessed profile of the surfaceof the printed circuit board by at least 0.1. Further, the laser maydecompose or remove contaminants from the surface of the PCB. The lasermay improve the coupling of the optical component to the printed circuitboard by increasing the roughness of the surface of the printed circuitboard and/or removing contaminants from the surface of the printedcircuit board. In configurations where a solder mask is applied to thesurface of the PCB, the laser may remove at least a portion of a soldermask on the PCB.

A characteristic of the laser such as the power, the intensity, and thewavelength of the laser may be selected to be sufficiently high toincrease the roughness of the surface and/or remove contaminants withoutdamaging the PCB and/or components coupled to the PCB. The desiredpower, intensity and wavelength of the laser may depend on materialsincluded in the PCB (e.g., layers of the PCB), materials of thecontaminants, materials of components coupled to the PCB, or anysuitable combination thereof. In one example, the laser may be anultraviolet laser, for example, a laser emitting electromagneticradiation within a range of ultraviolet wavelengths. In somecircumstances, ultraviolet wavelengths may include wavelengths betweenabout 100 nanometers (nm) and about 400 nm. In some configurations, thelaser may be about a 355 nm wavelength laser, although other suitableconfigurations may be implemented. Additionally or alternatively, insome configurations the laser may include a laser power of about 3 Watts(W).

Operation of the laser may be manually or automatically controlled usinga controller. The controller may specify where on the substrate or thePCB the laser is applied. For example, the pattern that the laser isapplied on the substrate or the PCB may correspond to thelaser-roughened area 112 (see FIGS. 1A-1C). As such, the pattern may beselected such that the laser forms the laser-roughened area 112. In someconfigurations, it may be possible to accurately control the laser toform the laser-roughened area 112 in specific areas on the surface ofthe substrate or the PCB.

At step 312, the surface of the substrate or the PCB may be visuallyinspected. Application of the laser to the surface of the substrate orthe PCB may visibly modify the surface in the area that the laser isapplied. In particular, the laser may be applied for a sufficient timeand duration to decompose a surface of the PCB such that thelaser-roughened area (e.g., the laser-roughened area 112) is visuallyperceptible. Accordingly, it may be possible to determine whether aportion of the PCB has been lasered, whether contaminants have beenremoved from a certain area on the surface and whether the area has beenroughened by visually inspecting the surface. For example, the laser maychange the color or texture of the surface where the laser is applied.In particular, the color or texture of the surface may be different inthe area because all or a portion of a layer may be removed by thelaser. Such configurations may also facilitate positioning of componentsto be coupled to the surface because the visibly modified surface mayindicate where the component should be attached to the surface.

Additionally or alternatively, visual inspection of the surface mayfacilitate in determining whether or not the laser was successfullyapplied to the surface, whether contaminants were removed in certainareas on the surface, and whether the surface was roughened in certainareas. In such configurations, components may be coupled to the surfacein areas where contaminants have been removed and/or have beenlaser-roughened.

At step 314, another component may be coupled to the surface of thesubstrate or the PCB. The component may be coupled to the surface at thecoupling area and/or the laser-roughened area formed by application ofthe laser. In some configurations, the component may be an opticalcomponent, such as lens, although the concepts described herein may beapplied to other types of components as well. The component may beattached at a coupling area on the surface of the PCB, and thelaser-roughened area may be positioned at least partially or fullyinside of the coupling area. The component may be coupled to the surfacein any suitable manner, and in some configurations an adhesive such asan epoxy may be used. In circumstances where the component is an opticalcomponent, the optical component may be optically aligned with one ormore optoelectronic component coupled to the surface.

In some configurations, the optical component may at least partiallyenclose the optoelectronic component(s) after the optical component iscoupled to the PCB. Additionally or alternatively, the optical componentmay hermetically seal the optoelectronic component(s) in between the PCBand the optical component. Accordingly, the optoelectronic component(s)may be hermetically sealed between the PCB and the optical componentafter the optical component is coupled to the PCB.

In some configurations, the method 300 may include attaching at leastone electrical component to the surface of the substrate or the PCB,such as the electrical components 104 a-e of FIGS. 1A-1B. In someconfigurations, the electrical component(s) may be coupled before thelaser is applied, although in other embodiments the laser may be appliedprior to or substantially concurrently with coupling the electricalcomponents. The electrical component(s) may be electrically coupled byconductive couplings such as traces, tracks, pads and/or other featuresetched from one or more layers of electrically conductive material, suchas copper. In some configurations, the electrical component(s) may besoldered to electrically and mechanically couple them to the substrateor the PCB.

One skilled in the art will appreciate that, for this and otherprocedures and methods disclosed herein, the functions performed in theprocesses and methods may be implemented in differing order.Furthermore, the outlined steps and operations are only provided asexamples, and some of the steps and operations may be optional, combinedinto fewer steps and operations, or expanded into additional steps andoperations without detracting from the disclosed embodiments.

FIG. 4 is flow chart of an example method 400 of forming a PCBA and/ormodifying a surface of the PCB, such as the PCBA 100 of FIGS. 1A-1B. Themethod 400 may include any suitable aspects of the method 300, or viceversa. Although illustrated as discrete blocks, various steps in FIG. 4may be divided into additional steps, combined into fewer steps, oreliminated, depending on the desired implementation.

The method 400 may begin at step 402, in which one or moreoptoelectronic components may be coupled to the surface of the PCB. Forinstance, the optoelectronic components 108 of FIGS. 1A-1B may becoupled to the surface of the PCB. Accordingly, at least oneoptoelectronic component may be coupled to a surface of the PCB. In someconfigurations, the optoelectronic component may be soldered to theconductive couplings of the PCB, thereby mechanically coupling theoptoelectronic to the PCB and electrically coupling the electricalcomponents to the conductive traces.

At step 404, the surface of the PCB may be lasered to form alaser-roughened area on the surface of the PCB. The laser may be appliedto a certain area on the surface of the PCB. For example, the laser mayapplied on portions of the PCB where it may be desirable to removecontaminants and/or increase the roughness of the surface. Inparticular, the laser may applied to a portion of the PCB where acomponent is to be coupled to the surface of the PCB. The area where thelaser is applied may be a laser-roughened area, and the area where thecomponent is coupled to the PCB may be a coupling area. The shape of thelaser-roughened area may correspond to the shape of the coupling area.In some configurations, the laser-roughened area is smaller than thecoupling area. The laser-roughened area may surround the optoelectroniccomponents in a plane defined by the PCB.

The laser may remove at least a portion of a layer of the PCB and/or mayincrease the roughness of the surface of the PCB. In some aspects, thelaser may increase the arithmetical mean deviation of the assessedprofile of the surface of the PCB by at least 0.1. Further, the lasermay remove contaminants from the surface of the PCB. The laser mayimprove the coupling of the optical component to the printed circuitboard by increasing the roughness of the surface of the printed circuitboard and/or removing removes contaminants from the surface of theprinted circuit board. In some configurations, a solder mask may beapplied over the PCB before the lasering. In such configurations, thelaser may remove at least a portion of a solder mask on the PCB.

The power, intensity and/or wavelength of the laser may be selected tobe sufficiently high to increase the roughness of the surface and/orremove contaminants without damaging the PCB and/or components coupledto the PCB. The desired power, intensity and/or wavelength of the lasermay depend on materials included in the PCB (e.g., layers of the PCB),materials of the contaminants, materials of components coupled to thePCB, or any suitable combination thereof. In one example, the laser maybe an ultraviolet laser, for example, a laser emitting electromagneticradiation within a range of ultraviolet wavelengths. In somecircumstances, ultraviolet wavelengths may include wavelengths between100 nanometers (nm) and 400 nm. In some configurations, the laser may bea 355 nm wavelength laser, although other suitable configurations may beimplemented. Additionally or alternatively, inn some configurations thelaser may include a laser power of 3 Watts (W).

In some configurations, the surface of the substrate or the PCB may bevisually inspected. Applying the laser to the surface of the substrateor the PCB may visibly modify the surface in the area that the laser isapplied. In particular, the laser may be applied for a sufficient timeand duration to decompose a surface of the PCB such that thelaser-roughened area is visually perceptible. Accordingly, it may bepossible to determine whether a portion of the printed circuit board hasbeen lasered, whether contaminants have been removed from a certain areaon the surface and/or whether the area has been roughened by visuallyinspecting the surface. For example, the laser may change the color ortexture of the surface where the laser is applied. In particular, thecolor or texture of the surface may be different in an area because allor a portion of a layer may be removed by the laser. Such configurationsmay also facilitate positioning of components to be coupled to thesurface, because the visibly modified surface may indicate where thecomponent should be attached to the surface.

Additionally or alternatively, visual inspection of the surface mayfacilitate in determining whether or not the laser was successfullyapplied to the surface, whether contaminants were removed in certainareas on the surface, and/or whether the surface was roughened incertain areas. In such configurations, components may be coupled to thesurface in areas where contaminants have been removed and/or have beenlaser-roughened.

At step 406, an optical component may be coupled to the surface of thePCB. The optical component may be coupled to the surface at the couplingarea and/or the laser-roughened area formed by applying the laser. Insome configurations, the optical component may be a lens, although theconcepts described herein may be applied to other types of components.The optical component may be attached at a coupling area on the surfaceof the printed circuit board, and the laser-roughened area may bepositioned at least partially or fully inside of the coupling area. Theoptical component may be coupled to the surface in any suitable manner,and in some configurations an adhesive may be used. In somecircumstances, the optical component may be optically aligned with oneor more optoelectronic component coupled to the surface.

FIGS. 5A-5B illustrate an optical component 550 coupled to the surfaceof the PCBA 100. In particular, FIG. 5A is a top schematic view of thePCBA 100 with the optical component 550 and FIG. 5B is a side schematicview of the PCBA 100 with the optical component 550 coupled to surface.In some configurations, the optical component 550 may be coupled to thesurface of the PCBA 100 at the coupling area 110 and/or thelaser-roughened area 112 formed by applying the laser (see FIG. 1A). Insome configurations, the optical component 550 may be a lens, althoughthe concepts described herein may be applied to other types ofcomponents. The optical component 550 may be attached at a coupling areaon the surface of the PCBA 100, and the laser-roughened area may bepositioned at least partially or fully inside of the coupling area. Theoptical component 550 may be coupled to the surface in any suitablemanner, and in some configurations an adhesive may be used. In somecircumstances, the optical component 550 may be optically aligned withone or more optoelectronic component coupled to the surface.

In some configurations, the optical component 550 may at least partiallyenclose optoelectronic components, such as the optoelectronic components108 of FIG. 1A, after the optical component 550 is coupled to the PCBA100. Additionally or alternatively, the optical component 550 mayhermetically seal optoelectronic components in between the PCBA and theoptical component 550. Accordingly, the optoelectronic components 108 ofFIG. 1A may be hermetically sealed between the PCBA 100 and the opticalcomponent 550 after the optical component 550 is coupled to the PCBA100. The optical component 550 may be a lens optically coupled oroptically aligned to the optoelectronic components 108.

In some configurations, at least one electrical component may beattached to the surface of the PCB, such as the electrical components104 a-e of FIGS. 1A-1B. In some configurations, the electricalcomponent(s) may be coupled before the laser is applied, although anysuitable configuration may be implemented. The electrical component(s)may be electrically coupled by conductive couplings such as traces,tracks, pads and/or other features etched from one or more layers ofelectrically conductive material, such as copper. In someconfigurations, the electrical component(s) may be soldered toelectrically and mechanically couple them to the substrate or the PCB.

In some circumstances, lasering the surface of the substrate or the PCBmay be improve the bond between the component and the surface. Inparticular, the laser may improve the coupling of the optical componentto the printed circuit board by increasing the roughness of the surfaceof the printed circuit board and/or removing contaminants from thesurface of the printed circuit board. Such configurations may improvebonds when adhesives are used, buy may also be similarly advantageous inother bonding mechanisms. Furthermore, the configurations describedherein may be used to avoid weak bonds, formed, for example, bycontaminants and/or smooth surfaces of the substrate or PCB.

When the concepts described are implemented to bond optical componentsto the PCB, the resulting bond may robustly secure the optical componentto the PCB. Furthermore, weak bonds may be avoided by removing anycontaminants from the surface of the PCB where the optical component isbonded to the PCB. In such circumstances, the bond formed may bestronger and therefore may not break over time. The stronger bond may beuseful during subsequent processing of the PCB to form theoptoelectronic assembly, because the bond will not break during handlingor subsequent processing. Additionally or alternatively, the strongerbond may not break after the optoelectronic assembly is manufactured,for example, during operation of the optoelectronic assembly. Suchconfigurations may also prevent optoelectronic assemblies from failingprematurely because weak bonds caused by smooth surfaces or contaminantson the surface of the PCB may be avoided.

Although the described configurations may be particularly advantageousto bond optical components to PCBs, in other configurations the conceptsdescribed herein may be applied to improve bonding between any componentand a PCB, for example, electrical components or any other componentthat may be bonded to a PCB.

The terms and words used in the description and claims are not limitedto the bibliographical meanings, but, are merely used to enable a clearand consistent understanding of the disclosure. It is to be understoodthat the singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to “a component surface” includes reference to one or more ofsuch surfaces.

As used herein, an “electrical component” refers to a component thatinvolves electricity, an “optical component” refers to a component thatinvolves electromagnetic radiation (e.g., visible light or others), andan “optoelectronic component” refers to a component that involves bothelectrical signals and optical signals, and/or the conversion ofelectrical signals to optical signals, or vice versa.

By the term “substantially” it is meant that the recited characteristic,parameter, or value need not be achieved exactly, but that deviations orvariations, including for example, tolerances, measurement error,measurement accuracy limitations and other factors known to thoseskilled in the art, may occur in amounts that do not preclude the effectthe characteristic was intended to provide.

Aspects of the present disclosure may be embodied in other forms withoutdeparting from its spirit or essential characteristics. The describedaspects are to be considered in all respects illustrative and notrestrictive. The claimed subject matter is indicated by the appendedclaims rather than by the foregoing description. All changes which comewithin the meaning and range of equivalency of the claims are to beembraced within their scope.

What is claimed is:
 1. An optoelectronic assembly comprising: a printedcircuit board including a laser-roughened area; at least oneoptoelectronic component coupled to a surface of the printed circuitboard; and an optical component attached to the printed circuit board ata coupling area defined by the optical component contacting the printedcircuit board, wherein the laser-roughened area is positioned entirelywithin the coupling area defined by the optical component contacting theprinted circuit board.
 2. The optoelectronic assembly of claim 1,wherein the optical component is coupled to the printed circuit boardusing an adhesive.
 3. The optoelectronic assembly of claim 1, whereinthe at least one optical component is optically aligned with theoptoelectronic component.
 4. The optoelectronic assembly of claim 1,wherein the laser-roughened area of the surface of the printed circuitboard is rougher than a remaining area of the surface of the printedcircuit board.
 5. The optoelectronic assembly of claim 4, wherein thelaser-roughened area of the surface of the printed circuit board has alarger arithmetical mean deviation than the remaining area of thesurface of the printed circuit board.
 6. The optoelectronic assembly ofclaim 4, wherein a difference between the laser roughened area and theremaining area of the surface of the printed circuit board is visuallyperceptible.
 7. The optoelectronic assembly of claim 1, furthercomprising a solder mask on the surface of the printed circuit board,wherein the solder mask is absent at the laser-roughened area of thesurface of the printed circuit board.
 8. The optoelectronic assembly ofclaim 1, wherein the laser-roughened area surrounds the at least oneoptoelectronic component in a plane defined by the printed circuitboard.
 9. The optoelectronic assembly of claim 1, wherein the at leastone optical component is a lens that at least partially encloses theoptoelectronic component.
 10. The optoelectronic assembly of claim 9,wherein the lens is optically aligned with the at least oneoptoelectronic component.
 11. The optoelectronic assembly of claim 9,wherein the lens hermetically seals the at least one optoelectroniccomponent.
 12. The optoelectronic assembly of claim 1, wherein at leasta portion of a layer of the printed circuit board is removed at thelaser-roughened area.
 13. The optoelectronic assembly of claim 1,wherein at least some contaminants are removed at the laser-roughenedarea.
 14. The optoelectronic assembly of claim 1, wherein the at leastone optical component at least partially encloses the optoelectroniccomponent, and the optoelectronic component is hermetically sealedbetween the printed circuit board and the optical component.
 15. Theoptoelectronic assembly of claim 1, further comprising at least oneelectrical component coupled to the surface of the printed circuitboard.
 16. The optoelectronic assembly of claim 15, further comprisingconductive couplings coupled to the at least one electrical component.17. The optoelectronic assembly of claim 15, wherein the at least oneelectrical component is soldered to the printed circuit board.
 18. Theoptoelectronic assembly of claim 1, further comprising an amplifiercoupled to the surface of the printed circuit board.
 19. Theoptoelectronic assembly of claim 1, further comprising a clock and datarecovery circuit, a digital signal processing circuits, a driver, adigital-to-analog converter, or a modulator coupled to the surface ofthe printed circuit board.
 20. The optoelectronic assembly of claim 1,wherein the printed circuit board is a multilayer printed circuit board.